diff --git a/deps/Boost/Boost.cmake b/deps/Boost/Boost.cmake
index 08b62b9fb8..1526928094 100644
--- a/deps/Boost/Boost.cmake
+++ b/deps/Boost/Boost.cmake
@@ -27,8 +27,15 @@ endif ()
 # Boost.Container's bundled dlmalloc passes int* where the Win32 Interlocked API
 # takes volatile long*; cl compiles that with a warning, clang errors out.
 set(_boost_c_flags_line "")
+set(_boost_cxx_flags_line "")
 if (MSVC AND CMAKE_C_COMPILER_ID STREQUAL "Clang")
     set(_boost_c_flags_line "-DCMAKE_C_FLAGS:STRING=-Wno-incompatible-pointer-types")
+    # The Visual Studio generator applies only the link language's flags to a
+    # project, and boost_container links as C++, so its C file never sees
+    # CMAKE_C_FLAGS. The C++ flags reach every file; keep CMake's defaults.
+    if (CMAKE_GENERATOR MATCHES "Visual Studio")
+        set(_boost_cxx_flags_line "-DCMAKE_CXX_FLAGS:STRING=${CMAKE_CXX_FLAGS} -Wno-incompatible-pointer-types")
+    endif ()
 endif ()
 
 orcaslicer_add_cmake_project(Boost
@@ -46,6 +53,7 @@ orcaslicer_add_cmake_project(Boost
         "${_context_arch_line}"
         "${_context_impl_line}"
         "${_boost_c_flags_line}"
+        "${_boost_cxx_flags_line}"
 )
 
 set(DEP_Boost_DEPENDS ZLIB)
diff --git a/deps/CMakeLists.txt b/deps/CMakeLists.txt
index ed3af70d03..4b1daf5aa8 100644
--- a/deps/CMakeLists.txt
+++ b/deps/CMakeLists.txt
@@ -184,6 +184,11 @@ function(orcaslicer_add_cmake_project projectname)
 
     if (_dep_msvc_gen)
       set(_gen CMAKE_GENERATOR "${DEP_MSVC_GEN}" CMAKE_GENERATOR_PLATFORM "${DEP_PLATFORM}")
+      # The toolset picks the compiler here, not the CMAKE_<LANG>_COMPILER
+      # forwarded below, so without it a clang-cl superbuild builds with cl.
+      if (CMAKE_GENERATOR_TOOLSET)
+        list(APPEND _gen CMAKE_GENERATOR_TOOLSET "${CMAKE_GENERATOR_TOOLSET}")
+      endif ()
     else()
       set(_gen "")
     endif()
diff --git a/deps/Draco/Draco.cmake b/deps/Draco/Draco.cmake
index 02ac7efe13..77f73684f6 100644
--- a/deps/Draco/Draco.cmake
+++ b/deps/Draco/Draco.cmake
@@ -7,4 +7,7 @@ orcaslicer_add_cmake_project(Draco
     ${_options}
     URL https://github.com/google/draco/archive/refs/tags/1.5.7.zip
     URL_HASH SHA256=27b72ba2d5ff3d0a9814ad40d4cb88f8dc89a35491c0866d952473f8f9416b77
+    CMAKE_ARGS
+        # The encoder and decoder tools duplicate draco.lib; see deps-windows.cmake.
+        "${DEP_LLD_FORCE_MULTIPLE}"
 )
\ No newline at end of file
diff --git a/deps/NLopt/NLopt.cmake b/deps/NLopt/NLopt.cmake
index fdd6341f2b..07afc95a48 100644
--- a/deps/NLopt/NLopt.cmake
+++ b/deps/NLopt/NLopt.cmake
@@ -8,6 +8,8 @@ orcaslicer_add_cmake_project(NLopt
     -DNLOPT_GUILE:BOOL=OFF
     -DNLOPT_SWIG:BOOL=OFF
     -DNLOPT_TESTS:BOOL=OFF
+    # testopt is built regardless of NLOPT_TESTS; see deps-windows.cmake.
+    "${DEP_LLD_FORCE_MULTIPLE}"
 )
 
 if (MSVC)
diff --git a/deps/OpenSSL/OpenSSL.cmake b/deps/OpenSSL/OpenSSL.cmake
index 2fb4b51757..4a2d49572b 100644
--- a/deps/OpenSSL/OpenSSL.cmake
+++ b/deps/OpenSSL/OpenSSL.cmake
@@ -80,6 +80,12 @@ ExternalProject_Add(dep_OpenSSL
     INSTALL_COMMAND ${_install_cmd}
 )
 
+if (CMAKE_GENERATOR MATCHES "Visual Studio")
+    # OpenSSL builds with cl, but MSBuild runs nmake in this project's toolset
+    # environment, and ClangCL's puts clang's headers first. Use the default.
+    set_target_properties(dep_OpenSSL PROPERTIES VS_PLATFORM_TOOLSET "$(DefaultPlatformToolset)")
+endif ()
+
 ExternalProject_Add_Step(dep_OpenSSL install_cmake_files
     DEPENDEES install
 
diff --git a/deps/deps-windows.cmake b/deps/deps-windows.cmake
index 6e73f7d4b5..4305489758 100644
--- a/deps/deps-windows.cmake
+++ b/deps/deps-windows.cmake
@@ -42,6 +42,15 @@ else ()
     message(FATAL_ERROR "Unsupported OS architecture: ${DEPS_ARCH}")
 endif ()
 
+# Draco's tools and NLopt's testopt compile sources that are also in their
+# static library. MSBuild passes the library before the objects and lld-link
+# resolves as it goes, so the library's copy wins and the object then reads as
+# a duplicate. Nothing uses those executables, so let lld keep the first one.
+set(DEP_LLD_FORCE_MULTIPLE "")
+if (CMAKE_GENERATOR MATCHES "Visual Studio" AND CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    set(DEP_LLD_FORCE_MULTIPLE "-DCMAKE_EXE_LINKER_FLAGS:STRING=${CMAKE_EXE_LINKER_FLAGS} /FORCE:MULTIPLE")
+endif ()
+
 if (${DEP_DEBUG})
     set(DEP_BOOST_DEBUG "debug")
 else ()